1. Field of the Invention
The present invention relates to a vehicle theft prevention device having a reduced load imposed on the vehicle's battery.
2. Description of the Background Art
General vehicle mounted, theft prevention devices are known in the art. Such theft prevention devices may include a sensor for sensing a vibration of the vehicle, or a sensor for sensing movement of the vehicle using infrared rays or ultrasonic waves. Such theft prevention devices may also include a detection means for detecting disconnection of a particular circuit of the vehicle. When an attempt is made to steal the vehicle, one of the sensors or the detection means generates a signal. In response to the signal, an alarm is activated or the vehicle is disabled.
It is also known to equip a motorcycle with a theft prevention device. Such a motorcycle mounted, theft prevention device can be activated and deactivated by a remote control. In such a theft prevention device, a receiver is mounted to the motorcycle. The receiver must always be in a powered, waiting state in order to receive a signal from the remote control. Therefore, an operating current is always flowing into the receiver from the vehicle's battery. Over an extended period of time, this operating current amounts to a large load to the vehicle's battery.
Japanese Laid-Open No. Sho 61-30451 discloses a vehicle theft prevention device in which a first transmitter, a first receiver, and a security mechanism are mounted to a vehicle. A second transmitter and a second receiver are part of a portable unit. The second transmitter transmits a faint signal and the first receiver receives this faint signal. When the vehicle and the portable control are separated by more than a predetermined distance, the faint signal from the second transmitter can no longer be received by the first receiver. When this situation occurs, the security mechanism is activated to prevent theft of the vehicle.
In the JP Laid-Open Sho 61-30451 theft prevention device, the first transmitter and first receiver, mounted to the vehicle, are always in an operating state. Therefore, an operating current is continually flowing into the first transmitter and first receiver from the vehicle's battery. Again, over an extended period of time, this amounts to a large load being imposed on the vehicle's battery.
In summary, in the prior art theft prevention devices, which include a remote control, a receiver mounted to a vehicle must always be powered. The receiver is always powered so that it will be able, at any instant, to receive a deactivation signal from a transmitter in the remote control. The deactivation signal is used by the theft prevention device to deactivate the sensors and to allow the vehicle to be normally operated. The continually powered receiver is a constant draw on the vehicle's battery. This draw, over an extended period of activation of the theft prevention device, can lead to the vehicle's battery becoming dead or weak.